Build your first Ruby on Rails app

Eric Dugre

13 minutes

0% complete

Create a basic Ruby on Rails app using the Delivery Ruby SDK.You’ll practice what you’ve learned in the previous lessons.

Create a new project

Prepare the environment

To begin your project, you’ll need Ruby 3.1 and Rails installed. You can get Ruby from ruby-lang.org. After that, install Rails using this command:

Shell

gem install rails

Create a blank Rails project

To create a new Rails project, we recommend using the –O parameter, which will create the project without a database. In this tutorial, you won't need a local database.

Shell

rails new kontentairails –O

Open your new Rails project in an IDE such as Visual Studio Code and open a file named Gemfile. Inside the file, you'll add Ruby gems that your project needs to run.

Add dependencies

In the Gemfile file, add the kontent-ai-delivery gem, and also the render_async gem

like this:

Ruby

gem 'kontent-ai-delivery'
gem 'render_async'

First run

At this point, you can run your Rails application by executing the following commands in your command line.

Ruby

bundle install
rails server

The first command installs the necessary Ruby gems and the second starts a local Rails server. Navigate to localhost:3000

in your browser and you'll see the default Rails welcome page:

Creating a controller and view

Rails creates the default controller /app/controllers/application_controller.rb to use in your application. Let’s modify it so that you can use the Kontent::Ai::Delivery::DeliveryClient in your controllers:

Ruby

class ApplicationController < ActionController::Base
  PROJECT_ID = '<YOUR_ENVIRONMENT_ID>'.freeze # PROJECT_ID identifies a project environment
  @@delivery_client = Kontent::Ai::Delivery::DeliveryClient.new project_id: PROJECT_ID
end

Create a new controller named home_controller.rb in the same directory. You'll use the controller to display a list of articles on the home page.

Ruby

class HomeController < ApplicationController
def index; end
end

For now, this controller has one action that will display index.html.erb. You’ll add the cool stuff in a bit! In the /app/views directory, create a new folder named home. Then create the index.html.erb file inside of it. You can add any HTML you want here. For tutorial purposes, let's use a placeholder for your list of articles.

HTML

<h1>Latest Dancing Goat Articles</h1>
<div>
 (coming soon)
</div>

Open the /app/config/routes.rb file and register our HomeController. Then tell Rails you want to view HomeController’s index() action when accessing the main domain.

Ruby

Rails.application.routes.draw do
  resources :home
  root 'home#index'
end

If you haven’t already, shut down the previous server by pressing CTRL + C in the command line and run the rails server command again to view your changes. There are no articles displaying yet, so let’s fix that.

Asynchronous rendering

You’re going to add a new action to the HomeController that will asynchronously request articles from Kontent.ai and display them on the home page. This is what the render_async gem is for: using this gem will allow your home page to load before Kontent.ai even responds, and the content will be rendered once it’s received. Note that this is not necessary, but may speed up your site. Later in this tutorial, you’ll create a controller that doesn’t use render_async. Let’s start with the required scripts for render_async to do its magic. Add the following to the app/views/layouts/application.html.erb file just above the closing </body> tag.

HTML

<body>
 <%= yield %>
 <%= content_for :render_async %>
</body>

In the app/views/home/index.html.erb file you need to tell render_async where to load your list of articles. Add the following block to the view where you want the articles to show.

HTML

<h1>Latest Dancing Goat Articles</h1>
<div>
  <%= render_async article_list_path %>
</div>

The render_async gem will request data from the article_list_path and load the response where the code block is placed. Let’s define the article listing path in app/config/routes.rb like this:

Ruby

Rails.application.routes.draw do
  resources :home
  get :article_list, :controller => :home
  root 'home#index'
end

Create an article_list action in your HomeController. This action will render a partial view when called.

Ruby

class HomeController < ApplicationController
  def index; end
  def article_list
    render partial: "article_tile"
  end
end

Finally, create a partial view n _article_tile.html.erb in the app/views/home folder which will render when the article_list action is called. It can contain anything right now.

HTML

<b>Articles are almost here..</b>

Run rails server and reload the home page. The render_async has rendered _article_tile.html.erb view within the index view.

Now for the fun stuff!

Adding Rails to Kontent.ai

It’s finally time to get some data from Kontent.ai and display it on the home page. You’ll be using the .items method and a few filtering options

. Change the body of your article_list action to the following.

Ruby

def article_list
  @response = @@delivery_client.items(
    'system.type'.eq 'article'
  )
  .order_by('elements.post_date', '[desc]')
  .execute
  if @response.http_code == 200
    render partial: "article_tile", collection: @response.items, as: :article
  else
    logger.info @response.to_s
    render html: 'Sorry, articles are not available at this time'
  end
end

So, what’s going on here? The client you defined in the ApplicationController controller is getting all content items from Kontent.ai of the “article” type and storing them in a variable which is passed to the _article_tile.html.erb file. If the response is successful, the app renders the view for each content item, which will be accessible in the partial view as article. Otherwise, the app logs some data about the response and renders plain HTML instead. Change the _article_tile.html.erb partial view to render a preview of each article and link to another page to read the full article.

HTML

<a style="color:black" href="/article/<%= article.system.codename %>">
 <div style="background-color:#eee;float:left;padding:10px;width:300px;height:400px;margin-bottom:20px;margin-right:20px;display:inline-block">
 <span style="font-weight:bold;font-size:1.3em"><%= article.elements.title.value %></span>
 <br><span style="color:#888"><%= DateTime.parse(article.elements.post_date.value).strftime("%A, %B %e, %Y") %></span>
 <br/><br/><img src=<%= article.get_assets('teaser_image').first.url %> style="width:100%" />
 <br/><span><%= article.elements.summary.value %></span>
 </div>
</a>

If you rerun the Rails server now, your home page will look like this.

Resolving rich text

Rich text elements, such as the one in our articles, can contain links to other content items, components, and many other things. You’ll now create a page that will display the article text, resolving any of these objects contained in the rich text field. First, create the ArticleController controller in /app/controllers which will use the codename of the article from the request to get the content item from Kontent.ai. A URL such as ~/article/some_code_name will automatically map to the controller’s show() action thanks to default routing rules

Ruby

class ArticleController < ApplicationController
  def show
    codename = params[:id]
    response = @@delivery_client.item(codename).execute
    if response.http_code == 200
      @article = response.item
      render partial: 'show'
    else
      logger.info response.to_s
      render html: 'The article you requested couldn\'t be found'
    end
  end
end

Ruby

Rails.application.routes.draw do
  resources :home, :article
  get :article_list, :controller => :home
  root 'home#index'
end

Now, create the _show.html.erb partial view in /app/views/article.

Ruby

<h1><%= @article.elements.title.value %></h1>
<%= @article.elements.body_copy.value.html_safe %>

If you run rails server now and access an article that contains inserted content items (e.g. /articles/ coffee_beverages_explained), you'll notice that the these content items are rendered with their <object> HTML tags like this.

HTML

<object type="application/kenticocloud" data-type="item" data-rel="component" data-codename="n373888cc_34e2_01e1_1820_3cb52ab1b2a1"></object>

This is meant to be a Hosted Video component, but you need to use the InlineContentItemResolver

to change how it appears in the app. Change /app/controllers/ApplicationController to use an inline item resolver.

Ruby

class ApplicationController < ActionController::Base
  PROJECT_ID = '<YOUR_ENVIRONMENT_ID>'.freeze # PROJECT_ID identifies a project environment
  item_resolver = Kontent::Ai::Delivery::Resolvers::InlineContentItemResolver.new(lambda do |item|
    if (item.system.type.eql? 'hosted_video') && (item.elements.video_host.value[0].codename.eql? 'youtube')
      return "<iframe class='hosted-video__wrapper'
                     width='560'
                     height='315'
                     src='https://www.youtube.com/embed/#{item.elements.video_id.value}'
                     frameborder='0'
                     allowfullscreen
                     >
             </iframe>"
    else
      return ''
    end
  end)
  @@delivery_client = Kontent::Ai::Delivery::DeliveryClient.new project_id: PROJECT_ID, inline_content_item_resolver: item_resolver
end

To get the resolved value for a content element you need to use the get_string method. Change the _show.html.erb partial view to use the method.

Ruby

<h1><%= @article.elements.title.value %></h1>
<%= @article.get_string('body_copy').html_safe %>

If you now access the /article/coffee_beverages_explained route in your browser, you’ll see the YouTube video rendered correctly in the article detail.

Resolving links

If a rich text element contains links to other content items, they will be rendered as empty <a> HTML tags by default. You can see an example of this on the /article/coffee_processing_techniques page of your application. To specify the URLs to other pages on your site, you need to implement a ContentLinkResolver

. In the /app/controllers/application_controller.rb controller, register a ContentLinkResolver similarly to the way the InlineContentItemResolver was created.

Ruby

link_resolver = Kontent::Ai::Delivery::Resolvers::ContentLinkResolver.new(lambda do |link|
  return "/coffees/#{link.url_slug}" if link.type.eql? 'coffee'
  return "/article/#{link.code_name}" if link.type.eql? 'article'
end)
@@delivery_client = Kontent::Ai::Delivery::DeliveryClient.new project_id: PROJECT_ID,inline_content_item_resolver:
item_resolver,content_link_url_resolver: link_resolver

If you now access the /article/coffee_processing_techniques route in your browser, the links to coffees on your site will correctly point to other pages such as /coffees/kenya-gakuyuni-aa!